Question Several questions during my first 2.4R2 build (mechanical part)

[jonesuki]

Just finished the mechanical parts of my first 3D printer build, a self-sourced 2.4R2 (300mm). Everything seems to be fine except the following few issues:

1. I cannot get the frame to be exactly square. There is ~1mm difference when I measured between two diagonal measures on 1 or 2 sides of the frame. The top side of the frame also not flush with my glass tabletop (~1mm raised at one corner). These happens whenever I tighten the screws. Is these acceptable or correctable in the future?
2. I had to install a 0.5mm shim on one end of both bed support extrusion, otherwise they will bend the bottom front and back extrusions when I tighten the screws. Is it an acceptable solution to add the shims?
3. When I tighten the screws on Z-motors, there was a click sound which sounded like something was clicked in place due to the torque. It happened to all four z-motor. Is that normal?
4. I bought the wrong rubber foot and now I had to install them with a M5x30 screws plus some shims & nuts. There is still about 5mm of the screws stick out inside the Z-belt-drive assembly, but have a few millimetres clearance to the gear. Is this acceptable or should I buy some M5x20 screw to replace them?
5. After installing the A/B belts, it required much more force to move along both X and Y rails compared to pre-belt-installation. I followed the instructions on Nero 3D de-racking video, successfully de-rack the gantry. But I noticed that he can move along the X/Y rails even after installing the belts (at 10:28) in a much smoother way than I do. Is this normal in my case? Is this related to the motor (LDO-42STH48-2004MAH in my case)?

Sorry for so many questions.

 

[m00dawg]

I can't give satisfactory answers to all those but for #1 at least, what I found helped was to apply pressure as I screwed the frame down. This can get a bit tricky. I used a spare extrusion or a builder's square to help. Doing that helped me square the frame up.

Though yes if it's not perfect, you can adjust this afterwards but you'll want is as accurate as you can get it. Being 1mm off might not matter depending on what you want to print, but that could throw off tolerances and things. I use Vector 3D's Califlower for adjusting skew and shrinkage. It worked very well.

 

[120decibell]

1. If it is less than 1mm out of square it should be fine. That is the level spec'ed in the assembly manual.
2. That sounds a little odd. Are any of the extrusions bent or not cut square?
3. That could have been the screws locating onto the flats on the motor shafts. Hard to tell. Kind of uncommon.
4. So long as they aren't rubbing on any belts or pulleys they should be fine.
5. Once the belts are installed the inherent drag of the motors will be noticeable. It shouldn't be really difficult though. Try unplugging the motors to ensure there is no additional back-emf braking. If they are still difficult double and triple check the belt routing, a misrouting of the belts in the AB drive assemblies is really common and will add a lot of drag.

 

[jonesuki]

I can't give satisfactory answers to all those but for #1 at least, what I found helped was to apply pressure as I screwed the frame down. This can get a bit tricky. I used a spare extrusion or a builder's square to help. Doing that helped me square the frame up.

Though yes if it's not perfect, you can adjust this afterwards but you'll want is as accurate as you can get it. Being 1mm off might not matter depending on what you want to print, but that could throw off tolerances and things. I use Vector 3D's Califlower for adjusting skew and shrinkage. It worked very well.

Thanks. I did what you said by applying pressure while screwing (with help from my kids and wife ). But still can’t get it perfect. It shifted a little bit when I tightened the screws fully.
The Califlower seems great. Gonna try it later. Thx.

 

[jonesuki]

1. If it is less than 1mm out of square it should be fine. That is the level spec'ed in the assembly manual.
2. That sounds a little odd. Are any of the extrusions bent or not cut square?
3. That could have been the screws locating onto the flats on the motor shafts. Hard to tell. Kind of uncommon.
4. So long as they aren't rubbing on any belts or pulleys they should be fine.
5. Once the belts are installed the inherent drag of the motors will be noticeable. It shouldn't be really difficult though. Try unplugging the motors to ensure there is no additional back-emf braking. If they are still difficult double and triple check the belt routing, a misrouting of the belts in the AB drive assemblies is really common and will add a lot of drag.

Thanks for your detailed reply.
1. That’s a relief.
2. I checked the extrusions before assembling and there is no bending or incorrect length. The cut seems to be square as well.
3. Screws everywhere seems to be normal.
4. Good to know. Thx.
5. I will double check the belt route.